Final answer:
The choice that consists only of polymers is D. Proteins, polysaccharides, nucleic acids, as fatty acids, amino acids, and sugars are not polymers but rather monomers or small molecules.
Step-by-step explanation:
The question asks which choice consists only of polymers. Polymers are large molecules composed of repeating structural units called monomers linked together. In the context of biology, important polymers include proteins, polysaccharides, and nucleic acids. Proteins are polymers of amino acids linked by peptide bonds, polysaccharides are carbohydrates formed by linking monosaccharides through glycosidic bonds, and nucleic acids like DNA and RNA consist of nucleotide monomers linked by phosphate diester linkages. Therefore, among the given choices, the one that only consists of polymers is D. Proteins, polysaccharides, nucleic acids. Fatty acids, amino acids, and sugars are not polymers; they are monomers or small molecules.